fix: harden workspace registry installation docs

scripts/test-verify-workspace-install-docs.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+# Regression test for copyable installation examples and secret-file validation.
+set -euo pipefail
+
+root="$(cd "$(dirname "$0")/.." && pwd -P)"
+output="$(mktemp "${TMPDIR:-/tmp}/thoth-install-docs-test.XXXXXX")"
+trap 'rm -f "$output"' EXIT HUP INT TERM
+
+"$root/scripts/verify-workspace-install-docs.sh" --fixtures-only >"$output"
+
+for fixture in \
+  "copied local base fixture" \
+  "copied server PostgreSQL/TLS fixture" \
+  "copied HTTPS Git override fixture" \
+  "copied SSH Git override fixture" \
+  "non-path secret-file fixture rejected"; do
+  grep -Fqx "$fixture passed" "$output" >/dev/null || {
+    echo "missing fixture verification: $fixture" >&2
+    cat "$output" >&2
+    exit 1
+  }
+done